1. Field of the Invention
The present invention relates to a device using a piezoelectric film, such as an actuator or sensor, etc., that uses a piezoelectric film.
2. Description of the Related Art
An inkjet printing head is known as an actuator that uses a piezoelectric film. An example of such an inkjet printing head is disclosed in Japanese Patent Application Publication No. 2013-215930. The inkjet printing head disclosed in Japanese Patent Application Publication No. 2013-215930 includes a nozzle substrate, a pressure chamber substrate, a vibrating film, and a piezoelectric element bonded to the vibrating film. A pressure chamber, into which ink is introduced, is formed in the pressure chamber substrate and the vibrating film faces the pressure chamber. The piezoelectric element is arranged by laminating a lower electrode, a piezoelectric film, and an upper electrode in that order from the vibrating film side.
Lead zirconate titanate (PZT: PbZrxTi1-xO3) is a perovskite ferroelectric substance, and sensors and actuators that make use of its excellent piezoelectric characteristics have been proposed. A piezoelectric film that uses PZT is formed by a sputtering method or a sol-gel method. The forming of a PZT film by a sol-gel method is described, for example, in Japanese Patent Application Publication No. 6-40727. The sol-gel method includes a coating process of coating on a precursor solution, containing PZT, to form a coating film, a drying process of drying the coating film, a prebaking process of heating the coating film after the drying process to make the coating film undergo gelling, and a main baking process of heat-treating and thereby sintering the gelled coating film. Ordinarily, the PZT film is formed by performing the main baking process after repeating a process, constituted of the coating process, the drying process and the prebaking process, a plurality of times. The piezoelectric film having a targeted film thickness is formed by such a series of processes being performed repeatedly. The piezoelectric film thus includes a plurality of laminated PZT layers.